In a test and measurement instrument, a word can be used as a condition for a trigger. For example, a trigger can be generated on the occurrence of a particular digital word on a probed data bus of a device under test. To generate such a trigger, digital comparators can be used to detect when two digital words match. Such circuitry can be implemented using discrete logic gates. For example, an input word can be bitwise exclusive-NOR'ed with a trigger condition word. For each of the resulting outputs, a do-not-care bit can be combined in a second logic gate. The resulting outputs, modified by the do-not-care bits can be combined together in logic circuitry to generate a signal indicating whether the trigger condition word occurred in the input word.
However, the above implementation results in at least a three gate delay through the word recognizer. Additionally, delay differences (skew) in the data bus, the probes, and/or the logic gates in the word recognizer may result in false recognition of a word when multiple bits of the data bus change substantially simultaneously.